Add BaseMemoryLib optimized for PEI

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@4035 6f19259b-4bc3-4df7-8a09-765794883524

MdePkg/Library/BaseMemoryLibOptPei/Ia32/CopyMem.S

@@ -0,0 +1,62 @@
+#------------------------------------------------------------------------------
+#
+# Copyright (c) 2006, Intel Corporation
+# All rights reserved. This program and the accompanying materials
+# are licensed and made available under the terms and conditions of the BSD License
+# which accompanies this distribution.  The full text of the license may be found at
+# http://opensource.org/licenses/bsd-license.php
+#
+# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+# Module Name:
+#
+#   CopyMem.Asm
+#
+# Abstract:
+#
+#   CopyMem function
+#
+# Notes:
+#
+#------------------------------------------------------------------------------
+
+.globl _InternalMemCopyMem
+
+#------------------------------------------------------------------------------
+#  VOID *
+#  EFIAPI
+#  InternalMemCopyMem (
+#    IN VOID   *Destination,
+#    IN VOID   *Source,
+#    IN UINTN  Count
+#    );
+#------------------------------------------------------------------------------
+_InternalMemCopyMem:
+    push    %esi
+    push    %edi
+    movl    16(%esp), %esi              # esi <- Source
+    movl    12(%esp), %edi              # edi <- Destination
+    movl    20(%esp), %edx              # edx <- Count
+    cmpl    %esi, %edi
+    je      L_CopyDone
+    cmpl    %edx, $0
+    je      L_CopyDone
+    leal    -1(%esi, %edx), %eax        # eax <- End of Source
+    cmpl    %esi, %edi
+    jae     L_CopyBytes
+    cmpl    %eax, %edi
+    jb      L_CopyBytes                 # Copy backward if overlapped
+    movl    %esi, %eax                  # esi <- End of Source
+    leal    -1(%edi, %edx), %edi        # edi <- End of Destination
+    std
+L_CopyBytes:
+    movl    %ecx, %edx
+    rep
+    movsb                               # Copy bytes backward
+    cld
+L_CopyDone:
+    movl    12(%esp), %eax              # eax <- Destination as return value
+    pop     %edi
+    pop     %esi
+    ret